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Thursday, 29 January 2015

Alcohol Puts You Right to Sleep, and Then It Doesn’t!

As scientists study how the brain works when you sleep, they find a nightcap can have a big impact

Drinking alcohol right before bed can certainly make you drowsy—but
will result in a night of poor sleep overall, according to new research
from Australia's University of Melbourne.

"Alcohol is not actually a particularly good sleep aid," Dr.
Christian Nicholas, a research fellow at the university's Sleep Research
Laboratory, told Wine Spectator. "Even though it may seem like
it helps you get to sleep quicker, the quality of the sleep you get is
significantly altered and disrupted."

For their recent study, published in Alcoholism: Clinical and Experimental Research,
Nicholas and co-author Dr. Julia Chan studied the sleep patterns of 24
college students—12 men and 12 women—ages 18 to 21, on three separate
nights. (The legal drinking age Down Under is 18.)
All subjects received both alcoholic drinks (orange juice with vodka)
and placebo drinks (orange juice with a vodka-dipped straw) over the
course of the experiment; alcohol content was adjusted for body weight,
designed to produce a peak blood-alcohol content (BAC) of 0.1 percent.
Subjects' sleep patterns were observed overnight by electroencephalogram
(EEG), which monitors electrical impulses in the brain.

Understanding sleep remains a relatively new scientific endeavor, and
research that employs an EEG is newer still. Previous studies focused
on the effects of alcohol and sleep have been inconclusive. Nicholas'
and Chan’s research builds upon these previous findings with a
more-comprehensive exploration of the effects of acute alcohol
consumption across different sleep cycles and in different brain
regions.

As anyone who’s gone to bed after several drinks will tell you,
alcohol initially put the subjects right to sleep, and they slept deeply
for the first half of the night. But the second half of the night
proved to be restless. "We showed that after pre-sleep alcohol
consumption there is an increase in slow-wave sleep early in the night,
and later in the night there is a lot of sleep disruption, greater
numbers of awakenings and more time spent awake," said Nicholas.

Slow-wave sleep is marked by high delta activity (delta waves are the
brain waves associated with the deepest level of sleep). In the second
half of the night, those who had consumed alcohol experienced what's
known as alpha-delta sleep—which means that alpha waves (those
associated with a state of calm wakefulness, such as would be achieved
in meditation) and delta waves were occurring at the same time."The
simultaneous increase in alpha power observed after alcohol, we believe,
indicates that NREM sleep [non-rapid eye-movement sleep, or dreamless
sleep] is being disrupted, and thus the normal restorative effects of
sleep are likely not being achieved," said Nicholas.

The reasons why alcohol affects sleep were not directly addressed
here, but one hypothesized mechanism has to do with a major inhibitory
neurotransmitter called GABA, which helps to regulate sleep. Nicholas
explained that alcohol can mimic or stimulate GABA activity, thus
interfering with its regulation.

Nicholas and Chan chose college students as their sample group
because sleep patterns tend to change significantly during late
adolescence—and so do alcohol-consumption habits. Adolescents show a
sharp decline in slow-wave sleep and delta activity frequency beginning
at the age of 12 and stretching sometimes into their twenties. Although
acute alcohol consumption might not change sleeping patterns
permanently, Nicholas noted, “it is highly likely that chronic drinking
does have effects on sleeping patterns, though it is unclear exactly why
the changes appear.”
So how should one proceed when it comes to wine before bedtime? "The
National Institute on Alcohol Abuse and Alcoholism [NIAAA, part of
America's National Institutes of Health] considers moderate drinking as
up to one drink per day for women and up to two drinks per day for men,"
said Nicholas. "Drinking at these levels is unlikely to significantly
disrupt your sleep. So if you are drinking, ideally BAC should be
minimized by the time you go to bed (meaning drinking in moderation and
stopping preferably several hours before bedtime), and ensuring that you
have adequate time in bed to get a good night’s sleep."